std::ranges::slide_view<V>::begin
constexpr auto begin()
requires (!(/*simple-view*/<V> && /*slide-caches-nothing*/<const V>));
| (1) | (since C++23) |
constexpr auto begin() const
requires /*slide-caches-nothing*/<const V>;
| (2) | (since C++23) |
Returns an iterator to the first element of the slide_view.
Let base_ be the underlying view, n_ be the window size, iterator be the iterator type.
return iterator<false>(ranges::begin(base_),
ranges::next(ranges::begin(base_), n_ - 1, ranges::end(base_)),
n_);
Otherwise, equivalent to
return iterator<false>(ranges::begin(base_), n_);
If V models
slide-caches-first this function caches the result within the cached_begin_ for use on subsequent calls. This is necessary to provide the amortized constant-time complexity required by the range.
2) Equivalent to
return iterator<true>(ranges::begin(base_), n_);.Return value
An iterator to the first element of slide_view, which points to the n_-sized subrange of the underlying view type: V for overload (1) or constV for overload (2).
Example
#include <iostream>
#include <ranges>
#include <string_view>
using namespace std::literals;
int main()
{
static constexpr auto source = {"∀x"sv, "∃y"sv, "ε"sv, "δ"sv};
auto view{std::ranges::slide_view(source, 2)};
const auto subrange{*(view.begin())};
for (std::string_view const s : subrange)
std::cout << s << ' ';
std::cout << '\n';
}
Output:
∀x ∃y
See also
| returns an iterator or a sentinel to the end (public member function) |
|
|
(C++23) | compares a sentinel with an iterator returned from slide_view::begin (function) |
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